A computer-based Eye-movement Controlled Display System is being developed to investigate basic questions about the nature of the perceptual and cognitive processes involved in skilled reading. Subjects (primarily college students) will read from text displayed on a computer-controlled cathode-ray tube, while the computer monitors the movements of their eyes. This system makes it possible to change the display from which they are reading, during the period of a saccadic movement, allowing modification of the stimulus pattern at specific locations in central or peripheral vision. Some of the questions being investigated with this system are: From what area around the fixation point does the reader pick up various types of useful visual information during a fixation? Does the stimulus pattern direct eye movements in reading? What aspects of a word are primarily used in its identification during reading? How much lag is there between the time the eye fixates a word, and the time that the information from that work is processed to different levels? Is the time spent fixating different segments of the text related to such factors as syntactic structure, processing demands of the text in that area, or relevance to the subject's purpose in reading?